I will be looking at this later in the week as of course my real work has interrupted :) Thanks for all of the valuable input!
Brrett
________________________________________
From: Rick Hillegas [rick.hillegas@oracle.com]
Sent: Friday, March 29, 2013 2:10 PM
To: derby-dev@db.apache.org
Subject: Re: Why is the optimizer choosing such a bad path
On 3/29/13 9:30 AM, Mike Matrigali wrote:
> On 3/29/2013 5:28 AM, Bergquist, Brett wrote:
>> Mike I have a reproducible case but the database is 132GB so it is
>> not practical. I am willing to dig in and try to help debug this.
>> On the issue that was pointed to, Mamta seemed to have used a debug
>> procedure that would print out more information on why the optimizer
>> is choosing what it does. This might be useful in this case as well.
>>
>> So if someone can point me in the right area of the code to start
>> looking and adding some debug that would be helpful. I have done
>> some fixes for Derby in the past so I am able to build and debug Derby.
>>
> That's great. I am out of my depth debugging optimizer problems,
> hopefully rick and/or mamta can help with that tool they were working
> on. I think rick did some work to make it easier to turn on/off using
> optional tools.
>
The simpler api to optimizer tracing is part of the 10.10.1 release
candidate which we're testing now. Instructions on how to use it can be
found in my 2013-03-14 comment on
https://issues.apache.org/jira/browse/DERBY-6022
Hope this helps,
-Rick